What exactly is Riba?

I know it means interest. I'm a 16 year old girl revert and I don't quite understand the laws of riba. For example, are phone contracts haram? Are scholarships haram? Is insurance haram? How can I avoid riba in a country like Canada, USA, etc? I want to know ahead of time so inshAllah I don't commit this major sin once I have moved out and start a family inshAllah.